Hollow stay bolt



Oct. 26, 1943, G. R. GRI-:ENSLADE ET AL 2,332,569

HOLLOW STAYBOLT Filed MaICh 8, 1940 lNvx-:NTOR Gran/er1?. Greensl a d6 Tre deri duff. L Landgraf' sure that the holes are open.

Patented Oct. 26, 1943 l HOLLOW STAY BOLT Grover It. Greenslade, Scott Township, Allegheny County, and Frederick K. Landgraf, Grafton, v Pa., `assignors to Flannery `Bolt Company, Bridgeville, Pa., a corporation of Delaware Application March 8, 1940, rSerial No, 322,950

v4 claims. (o1. :a5-1.5) Y

This inventionrelates to hollow staybolts. The

`invention pertains especially to the protection of hollow staybolts having the hollow interior thereof coated with a relatively low melting point metl al as for example, lead or terne. i

ABoiler staybolts are usually made of Wrought iron or steel. Theyare commonly provided with a longitudinally extending opening that passes part Way orentirely through the length of the bolt and which is referred to in the trade as a telltale hole. If the bolt becomes cracked or fractured, Water will leak from the boiler into the hole Where its presence maybe noted, possibly during the operation of the boiler or when the boiler is put under hydrostatic test. In the operation of the bolts, rustrands'cale may formvin the holes or various accumulations of foreign materials may become impacted in the holes. Such an accumulation of foreign matter may be suihcient to clog the telltale hole and prevent the leakage of water through a fractured bolt from being indicated during inspection. Therefore it is necessary to test the bolts from time to time to make This is accomplished by an-electrical probing instrument that is inserted into thehole.

In order tov prevent the formation of rust in the holes it is common' practice `to copperplate the interior ofthe boltby an electroplating procl ess. Boltsare quite long as compared to the'diameter and they maybe as much as 30 or more in length while the telltale hole-is of a diameter much less than the full diameter of the bolt.` The `copperplating of the interior of such a long Small hole is diflicult, and it is not practical to make any adequate inspection to determine how corn- -pletely the copperpla'tingr covers the interior of the hole. It sometimes'happens that the copper is not deposited on some portion of the interior of the hole. This is especiallytrue where the wrought iron contains an exposed seam of slag in the Wall'of the hole. v

When i copperplating alone is' employed and there is some defecty in the copperplating, corrosive Water entering the telltale hole attacks the iron or steel of the bolt by getting underneath the copperplated layer at the lines of discontinuity caused by theslag seams. The 'copper is, therefore,undermined in such cases and the corrosion is accelerated by the electrolytic action caused by two dissimilar metals -in contact' in the presence of an'electrolyte. In 'many cases this degenerative action continues until the telltale hole has filled up Witha hard deposit ofproducts of cor- A, rosion. v

`According to the present invention the interior of the holes are hot coated With a low melting point metal as for example, lead or terne coating'.

VThe lead or terne coating forms a continuous lm over the interiorof the hole of the bolt. If the tern'ecoated bolt thenhas the interior Wall electroplated With copper, the copper lm Will be continuous. The ternecoating of the interior of the bolt thus assures that any copperplating Which is doney Will be continuous. Even lthough the copperplating were not continuous, the terne would resist rusting or corrosion of the'bolt from the inside out, and even though only the terne v.coating is used Without the copper, the terne orflike coating will be Vmore satisfactory than acopperplated coating alone would be for the reason that the terne coating Will be continuous and free of defects and because it will prevent leakage Where there is a slag seam of the character above referred to.

Inthermanufacture of staybolts it is frequently the practice to carburize or case harden the heads ,of the bolts by a cyaniding process requiring of course the heating of the bolts and the immersion of the ends of the bolts in a molten cyanide bath. According ltothe present invention the coating of the interior of the holes With a metal such as terne is accomplished in conjunction with'the cyaniding process. This enables the same equip- Vment to be'used Vthat* is used in connection with the cyaniding, and the low melting point metal .which is used as a coating material is heated and melted'While the bolts are being raised to a temperature to be carburized.

The natureof our invention may be' more fully :understood bylreferenc'e to the method of vproducing the bolts. `In practice, after they have'be'en drilled and When they are prepared for cyaniding 'they .are lled with a fluxingl solution as Vfor exampleaV zincchlorde solution. A piece of solid coating` `metal as for example fa short rod of lead the slug .orpiece of metal Which has `previously been chargedv into the hole and the bolt is placed `inv a 'basket along With other bolts which have been similarly treated, and the bolts, particularly the lower ends of them, are heated up inl prepara- 50 -irig of Ithe bolts evaporates the flux from the bolts tion for the cyaniding process. The Arlrst heatand the slug of coating metal is of course` melted. The Weighted rod Whichis of a diameter closely 55 'approximating the diameter of the hole in the boltfthen serves to displace the molten metal in metal isthe bottom of the hole so that the molten metal is forced upwardly around the rod and spread over the sides of the hole to form a coating. Preferably enough coating. metal is used so that a slight excess will now out the top of the bolt thus assuring the complete formation of a coating overthe .entire .surface of ,the hole... .1.1i order to prevent the .coating metal from flowing back into the bottom of the hole the rods are left in place and the bolts are transferred to the cyanide,

ing furnace where the ends of the bolts are imi-'iY mersed in molten cyanide. removed from the cyaniding furriie and before When the bolts 1;

they have had a chance tonce'ol, `the operator* withdraws the Weighted iron rods from Ythe 'holes I in the bolts and plunges the heads of the bolts into a bath of water or cooling fluid. Before quenching the head of the bolt the loperatorusually inverts it and strikes it against, a metal block While so inverted to remove any excess of the terne coating. It is of course vimportant .that

' v,the .weighted lreds be withdrawn before the bolts has been.previously hot coated with lead or other metal. x A rack .29, illustrated in Figure 1, is used in `preparing lthe Sbo'lts. It comprises an elongated `pan to .of .relatively shallow .depth and set into this pan is an elongated trough-likeystructure 31. Within the trough 3i areiongitudinally .extending plates v.or guides .'32 Ywhich .arexslightly inclined'with reference to 4a vertical plane, the arrangement being such that the bolts designated yA may be lstood ends/vise 2in rows in the Atrougl'i 29, the bolts leaning against the supports 32. 1 fIn the practice A.of lour yinvention the bolts, after they have been formed, .are arranged in vrot/sin `the rack :28. Located above the rack is a reservoir 33 which holds a liquid .flux such .a zinc chloride solution. At the bottom of the tank or .reservoir 33 yis .a yalved outlet `il! to Iwhich .connected a rubber tube 3.5, having a nozzle 3sat its `free end..

the rack `29 has heenn'lled eter slightly less than the hole in the bolt so that the rod will easily flt into .this hole. l When the bolts have been thus prepared they are charged ratos which ispreferably used .is Illllyshown and Y n described in our copendingiapplication Serial No.

376,600, filed Jan. 30, 1941. Upon being placed in ,the carrier as above indicated, the bolts are tlrst f f initially heated. In this initial heating all of the '-ligiiidfgflux in the bolts is evaporated and the bolts are heated to la temperature sulicient to l melt `,theslug oflcoating-metal. As the slugs of f coating 'inet'al melt, the rods E exert a pressurey .0.11 .themol-ten metal forcing the molten metal from the bottoms of the boltsup around the rods -tother'eby .coat the holes in the bolts throughout their entire length. The slugs D are preferably bolts, the opera-tor .turn `iills the. interior v i each bol-t with sol 1011 from .the mixing tank.

hissoiution is'desig. d G in A.Figline 4r. Asthe are filled with solution. a slug D .of coating y uarmed into cochone.. lheslug is pref- 'e 'bly for-med fiom a .length .of .rod .or .wire .of a diameter :such that'it yeasily bedropped `into .the hole in the belt *.It may be of lead or a lead alloy steh is used :in olf-ming .terneplata tm, seid-er, or `anyother d red low melting point metal, although the boating metal Yshcnnd of coursebe one that does not-.have a melting point Ylower than the temperature .to which the `bolt is ...subjected in operation which, intl-1e ease of high pressure `boiler-s meri be in -eseess of 4.9.09 F. After the' $11.15 has been charged .into the bolt, .a rod E is set into the-eilen end of the bolt, thisrod preferably having a .small'weisht e at the upper end iiiefff iliefiod, .be-.ills of e length .greater than Y the depth iii-tbe hele -the beltaudof .a diam- .Upon being .heated to this temperature., theearrfiel' is lowered into a cyanide bath :to .caserharden ,i .or .carbu ze the..heaci-s'l3Y-cfrtl-1e bolts.;

the @yam-ding opeiation'the-.rods keep :themolv-fteii solder spread over the interiors of the holes .ofthe bolts-.and prevent. the :solder yfrom running .baeloeiomiinioth oottomsof-theheies.

...Aitor the iigooerationhas Abeeneonnpleted the .bolts are lient .het until :such as the operator. opportunity .tovrexnove the reds .1Ef operaterfremoyesthe rods E, .one at a time. from the: belts.. .Ashememoves each bolt he .withdraws the red Etherefrom, inverts .the :bolt .manipulatingitso as, to dump .ouhany ,excess of the .coating .metaljpre-ferably .striking v, .the `belt 'when so .inverted against a solid metal 'block order tf1-assure ofthe excess metalfxunning out after which he quenehes-the headof Ithe .be desirable to copperooat. .the interior .or ther holes. The method .of eopperplating now'gen'er- ,allyfernployed for coating the -interiorof .stayhelts may be used. Acoordingto this method ther -steyboltsare arranged one rack I0. v`.Inii'isure 2 e tsingle staybeltldesienated A is shown. -A hollow plating electrode @l is entered .into the .hole in fthe bolt, the :electrode-having insulating .rings 4:2

thereon regularly. spaced intervals.' the purpose being to .hold the electrode centrally positiouedin the hole .of the bolt., Eleotrolyte is s'upplied'tothe interior of the bolt through a tube .n.3 4at thetop Vo f the hollow V.electrode 4I.

One side of a source of plating current indicated at i4 is connected to the rack 40 andthe other side .oi this souree of Current is connected .through a Wiretothe plating electrode 41| The electrodes.

being' coated, .the electroplating'rnechanism pery sezforming no part ofithe present invention; 'Ihe 'electrode Ais adjusted vertically so thatuwhile its `lowermcst,er-.1d -will be close .to 'the .bottom of the hole, it will never in fact contact the Abottom v 2,332,569 `of the ilo-1e. Vey eie'ctoplating the interior of a bo-lt which has been Apreviously terneplated or otherwise coated with a low melting point metal, the boltwill have a maximum resistanceto corrosion and the interior will have a surface of good electrical properties for the testing of the bolt. Since the ternecoating will completely cover areas to which the electroplating would not adhere and the copper will cover completely the ternecoatingacontinuous protective lm of copper is assuredover the entire interior of the bolt and as heretofore explained, thi'sicannot be Secured With assurance Where the hoty metal coating is not`rst applied `tothe interior of the hole. The metal referred to as ternecoating 'metal is an alloy of lead and tin in'whiclil the lead very greatly predominates. fAlloys for terneplating are extensively used in the steel industry and its composition is'well knownz to thosejskilled in the art. It is of course Acontemplatedthatin lieu of a terne-forming alloy, other` metals could be used as for example,y leadi or tin or zinc or Varv Y 3 The method and apparatus `herein disclosed constitute the subjectof our co-pending appli- ,cation Serial No. 376,600 filed January 30, 1941,

as a continuation-impart of thepresent application and in which the method and apparatus are more4 fully and completely described and claimed.

While yWe have illustrated and described cer-y tain specific embodiments of our invention, it will be 4understood, that various-changes and modications,y may be made therein and that ydifferent apparatus` may 'be substituted for the apparatus illustrated` within the scope of the following claims.

We claim:

1,V As a new article of manufacture, a hollow' i staybolt having the interior thereof hotcoated ious mixtures thereof, bearing in 'mind that `the coating metal should be one which is not melted at the temperature reached inside the Jboiler.

Usually a metal of the class comprising lead, tin and `zinc would be employed. I Y

In some cases it may be desirable i troplate the boltsand then coat them4 With the coating metal, and my invention `contemplates a bolt made whereV there is such a reversal of the process, although the present preferred method is to first apply the vcoating metal and then electroplate until the coating vmetal will cover those surfaces whichY may contain seams and which would interfere with the continuity of the layery of electroplated metal if the terne or similar coating Were not rst provided.

While we havel described the preferred method of constructing `a bolt embodying our invention, i the bolt may be made by other methods than the typical one herein described.

With a `non-ferrous metal and having a protective coating electrically deposited over said rst coating' 2,'As anew article of manufacture, a `lioll-ovv` vstaybolt Yhaving the interior thereof hot coated rwith anon-ferrous metal to provide a lining over the interior of the bolt, and an electricallydeposited film of copper over said rst film;

3. As a new article of manufacture, a ferrous staybolt having a telltale hole therein, the hole havinganon-ferrous hot-applied metal coating" over the Walls thereof and having an electrodeposited` coating over the walls thereof of a non-ferrous metal different'from the hot coating, one of said coatings-overlying the other, a portion of the staybolt being carburized.

4. As a new article of manufacture, a staybolt having a carburized head and having a tell-tale i hole therein of small diameter, `the interior Walls of the hole being completely hot coated with a metal of the group comprising lead, zinc and tin forming a continuous corrosive resistant coating.

GROVER R. GREENSLADE.. FREDERICK K; LANDGRAF. 

